The methods of the prior art for the preparation of 2-aryl benzoxazoles can be reduced to two basic patterns. In both cases, o-aminophenols are starting materials. In the one method, these are reacted with aromatic carboxylic acids or their derivatives, usually acid chlorides, to form o-hydroxybenzanilides, and then these are cyclized in a second step, usually with the aid of catalysts. The other method produces azomethines through reaction with aromatic aldehydes. The cyclization to benzoxazole is then performed by means of an oxidant. The same procedural steps can be applied for the preparation of 2-aryl benzothiazoles, using o-amino thiophenols as starting materials,
Benzoxazoles and benzthiazoles are the basis of numerous optical brighteners. Furthermore, compounds having a benzoxazole structure find use in dyes, cosmetics, pharmaceuticals and heat-resistant fibers.